The broad objectives of this project are 1) to define the limites of static SIMS in the quantitative monitoring of reactions occuring on organic surfaces, and 2) to develop static SIMS as a quantitative tool for determining the yields of surface modification reactions of biomedical importance. Toward this end, the relationship between the composition and microroughness of model organic surfaces and relative yields of molecular ions characteristic of the chemical structure of those surfaces is being studied. Current work is focused on static SIMS of model organic surfaces of patterned self-assembled monolayers (SAMs) formed by the adsorption of one or more (-functionalized n-alkane thiols on gold.